A Theory Of Everything?
Page 3
21St CENTURY PHYSICS
Not surprisingly, the mathematics of the 10th dimensional superstring is
breathtakingly beautiful as well as brutally complex, and has sent shock
waves through the mathematics community. Entirely new areas
of mathematics have been opened up by this theory.
Unfortunately, at present no one is smart enough to solve the
problem of a quantum black hole. As Edward Witten of the Institute for
Advanced Study at Princeton has claimed, "String theory is 21st century
physics that fell accidentally into the 20th century.
However, since the stakes are so high, that hasn't stopped teams of
enterprising physicists from trying to solve superstring theory.
Already, over 5,000 papers have been written on the subject. As Nobel
laureate Steve Weinberg said, "how can anyone expect that many of the
brightest young theorists would not work on it?"
Progress has been slow but steady. Last year, a significant breakthrough
was announced. Several groups of physicists independently announced that
string theory can completely solve the problem of a quantum black hole.
(However, the calculation was so fiendishly difficult it could only be
performed in two, not 10, dimensions.)
So that's where we stand today. Many physicists now feel that it's only
a matter of time before some enterprising physicist completely cracks
this ticklish problem. The equations, although difficult, are
well-defined. So until then, it's still a bit premature to buy tickets
to the nearest wormhole to visit the next galaxy or hunt dinosaurs!
WHAT HAPPENED BEFORE THE BIG BANG?
Einstein's theory of gravity, which gives us the Big Bang theory and
black holes, was subjected to the most stringent test yet and passed
with flying colors. In the latest (Oct.) issue of Physics Today,
astronomers from Harvard, MIT, and the Haystack Observatory proudly
announced that they had confirmed Einstein's theory to within an
astonishing .04% accuracy by measuring the bending of radio waves from
the quasar 3C279 near the edge of the visible universe.
But there is some irony in this announcement. Each success only
highlights a yawning gap. Even as scientists hail ever more accurate
tests of Einstein's theory of warped space, Einstein himself knew that
his theory broke down at the instant of the Big Bang. The theory had
feet of clay.
Relativity was worthless, he realized, when it came to answering the
most embarrassing cosmic question in all of science: What happened
before the Big Bang? Ask any cosmologist this question, and they will
throw up their hands, roll their eyes, and lament, "This may be forever
beyond the reach of science. We just don't know."
Until now, that is.
A remarkable consensus has been developing recently around what is
called "quantum cosmology," where scientists believe that a merger of
the quantum theory and Einstein's relativity may resolve these sticky
theological questions. Theoretical physicists are rushing in where the
angels fear to tread!
In particular, an appealing but starting new picture is emerging in
quantum cosmology which may be able to synthesize some of the great
mythologies of creation.
There are two dominant religious mythologies. According to
Judeo-Christian belief, the universe had a definite beginning. This is
the Genesis hypothesis, where the universe was hatched from a Cosmic
Egg. However, according to the Hindu-Buddhist belief in Nirvana, the
universe is timeless; it never had a beginning, nor will it have an end.
Quantum cosmology proposes a beautiful synthesis of these seemingly
hostile viewpoints. In the beginning was Nothing. No space, no matter or
energy. But according to the quantum principle, even Nothing was
unstable. Nothing began to decay; i.e. it began to "boil," with billions
of tiny bubbles forming and expanding rapidly. Each bubble became an
expanding universe.
If this is true, then our universe is actually part of a much larger
"multiverse" of parallel universes, which is truly timeless, like
Nirvana.
As Nobel laureate Steve Weinberg has said, "An important implication is
that there wasn't a beginning; that there were increasingly large Big
Bangs, so that the [multiverse] goes on forever - one doesn't have to
grapple with the question of it before the Bang. The [multiverse] has
just been here all along. I find that a very satisfying picture."
Universes can literally spring into existence as a quantum fluctuation
of Nothing. (This is because the positive energy found in matter is
balanced against the negative energy of gravity, so the total energy of
a bubble is zero. Thus, it takes no net energy to create a new
universe.)
As Alan Guth, originator of the inflationary theory, once said, "It's
often said there is no such thing as a free lunch. But the universe
itself may be a free lunch."
Andre Linde of Stanford has said, "If my colleagues and I are right, we
may soon be saying good-bye to the idea that our universe was a single
fireball created in the Big Bang."
Although this picture is appealing, it also raises more questions. Can
life exist on these parallel universes? Stephen Hawking is doubtful; he
believes that our universe may co-exist with other universes, but our
universe is special. The probability of forming these other bubbles is
vanishingly small.
On the other hand, Weinberg believes most of these parallel universes
are probably dead. To have stable DNA molecules, the proton must be
stable for at least 3 billion years. In these dead universes, the
protons might have decayed into a sea of electrons and neutrinos.
Our universe may be one of the few compatible with life. This would, in
fact, answer the age-old question of why the physical constants of the
universe fall in a narrow band compatible with the formation of life. If
the charge of the electron, the gravitational constant, etc. were
changed slightly, then life would have been impossible. This is called
the Anthropic Principle. As Freeman Dyson of Princeton said, "It's as if
the universe knew we were coming." The strong version of this states
that this proves the existence of God or an all-powerful deity.
But according to quantum cosmology, perhaps there are millions of dead
universes. It was an accident, therefore, that our universe had
conditions compatible with the formation of stable DNA molecules.
This leaves open the possibility, however, that there are parallel
universes out there which are almost identical to ours, except for some
fateful incident. Perhaps King George III did not lose the Colonies in
one such universe.
However, I can calculate the probability that one day you might be
walking down the street, only to fall into hole in space and enter a
parallel universe. You would have to wait longer than the lifetime of
the universe for such a cosmic event to happen. So I guess the United
States is safe for the present!
As J.B.S. Haldane once said, "the universe is not only queerer than we
suppose, it is queerer than we can suppose."
Dr. Michio Kaku is Prof. of theoretical physics at the City Univ. of New
York and author of Hyperspace: a Scientific Odyssey through the 10th
Dimension (Oxford Univ. Press).
HYPERSPACE: A SCIENTIFIC ODYSSEY THROUGH THE TENTH DIMENSION
Dr. Michio Kaku is professor of theoretical physics at the CUNY Graduate
Center and CCNY. This article is adapted from his next book, Hyperspace:
A Scientific Odyssey through Parallel Universes, Time Warps, and the
10th Dimension (Oxford). He is the author of Introduction to
Superstrings (Springer-Verlag).
Do higher dimensions exist? Are there unseen worlds just beyond our
reach, beyond the normal laws of physics?
Although higher dimensions have historically been the exclusive realm of
charlatans, mystics, and science fiction writers, many serious
theoretical physicists now believe that higher dimensions not only
exist, but may also explain some of the deepest secrets of nature.
Although we stress that there is at present no experimental evidence for
higher dimensions, in principle they may solve the ultimate problem in
physics: the final unification of all physical knowledge at the
fundamental level.
My own fascination with higher dimensions began early in childhood. One
of my happiest childhood memories was crouching next to the pond at the
famed Japanese Tea Garden in San Francisco, mesmerized by the
brilliantly colored carp swimming slowly beneath the water lilies. In
these quiet moments, I would ask myself a silly question that a only
child might ask: how would the carp in that pond view the world around
them?
Spending their entire lives at the bottom of the pond, the carp would
believe that their "universe" consisted of the water and the lilies;
they would only be dimly aware that an alien world could exist just
above the surface. My world was beyond their comprehension. I was
intrigued that I could sit only a few inches from the carp, yet we were
separated by an immense chasm.
I concluded that if there were any "scientists" among the carp, they
would scoff at any fish who proposed that a parallel world could exist
just above the lilies. An unseen world beyond the pond made no
scientific sense.
Once I imagined what would happen if I reached down and suddenly grabbed
one of the carp "scientists" out of the pond. I wondered, how would this
appear to the carp?
The startled carp "scientist" would tell a truly amazing story, being
somehow lifted out of the universe (the pond) and hurled into a
mysterious nether world, another dimension with blinding lights and
strange-shaped objects that no carp had ever seen before. The strangest
of all was the massive creature responsible for this outrage, who did
not resemble a fish in the slightest. Shockingly, it had no fins
whatsoever, but nevertheless could move without them. Obviously, the
familiar laws of physics no longer applied in this nether world!
THE THEORY OF EVERYTHING
Sometimes I believe that we are like the carp living contently on the
bottom of that pond; we live our lives blissfully ignorant of other
worlds that might co-exist with us, laughing at any suggestion of
parallel universes.
All this has changed rather dramatically in the past few years. The
theory of higher dimensional space may now become the central piece in
unlocking the origin of the universe. At the center of this conceptual
revolution is the idea that our familiar three dimensional universe is
"too small" to describe the myriad forces governing our universe.
To describe our physical world, with its almost infinite variety of
forms, requires entire libraries overflowing with mountains of technical
journals and stacks of obscure, learned books. The ultimate goal of
physics, some believe, is to have a single equation or expression from
which this colossal volume of information can be derived from first
principles.
Today, many physicists believe that we have found the "unified field
theory" which eluded Einstein for the last thirty years of his life.
Although the theory of higher dimensional space has not been verified
(and, we shall see, would be prohibitively expensive to prove
experimentally), almost 5,000 papers, at last count, have been published
in the physics literature concerning higher dimensional theories,
beginning with the pioneering papers of Theodore Kaluza and Oskar Klein
in the 1920's and 30s, to the supergravity theory of the 1970s, and
finally to the superstring theory of the 1980s and 90s. In fact, the
superstring theory, which postulates that matter consists of tiny
strings vibrating in hyperspace, predicts the precise number of
dimensions of space and time: 10. (See xxxx issue of Thesis.)
WHY CAN'T WE SEE THE FOURTH DIMENSION?
To understand these higher dimensions, we remember that it takes three
numbers to locate every object in the universe, from the tip of your
nose to the ends of the world.
For example, if you want to meet some friends in Manhattan, you tell
them to meet you at the building at the corner of 42nd street and 5th
avenue, on the 37th floor. It takes two numbers to locate your position
on a map, and one number to specify the distance above the map. It thus
takes three numbers to specify the location of your lunch. (If we meet
our friends at noon, then it takes four numbers to specify the space and
time of the meeting.)
However, try as we may, it is impossible for our brains to visualize the
fourth spatial dimension. Computers, of course, have no problem working
in N dimensional space, but spatial dimensions beyond three simply
cannot be conceptualized by our feeble brains. (The reason for this
unfortunate accident has to do with biology, rather than physics. Human
evolution put a premium on being able to visualize objects moving in
three dimensions. There was a selection pressure placed on humans who
could dodge lunging saber tooth tigers or hurl a spear at a charging
mammoth. Since tigers do not attack us in the fourth spatial dimension,
there simply was no advantage in developing a brain with the ability to
visualize objects moving in four dimensions.)
Sheila Na Gig
Send e-mail to mapona@yahoo.com
Copyright © 1999 Sheila Na Gig.
Page created 17 October 1999. Last updated 17 October 1999 at 11:53 AM.
Produced with Webford 2.01.